I was a programmer for a vibration analysis company before and during college and I'm a pretty big nerd in general so I am intimately familiar with signal-to-noise. I agree that this is the sole determinant of DR as measured scientifically. By no means however is this the end of the story for those who are interested in the final image.
Most people mean DR as "how much of the scene's shadows and highlights I can put on paper (or into web pixels or whatever)". In this practical context the ability for the software to reach into the recorded signal and render out meaningful, color accurate, and detailed information is as much a part of the equation as anything else. One huge example is the black-cal file (taken even at short shutter speeds) which isolates the quantity and type of noise on the sensor in order to suppress it during processing. Only Phase One software can access that black-cal file and that information helps reduce shadow noise (also helps lengthen the max exposure times) with minimal lose of real data.
I imagine you and I can have a very informed and excruciatingly technical conversation about the theoretical or scientifically measured DR of various digital backs and cameras. Provided that someone wants to shoot line charts, step patterns then that conversation would prove meaningful. For practical applications however the software, the type of noise, the color accuracy of shadows, and the ease of playing with the reproduced DR of the file are all important.
If this discussion seems overly technical to some then here is the summary:
If you shoot a difficult scene with a D3X and a Phase Back* and handle each well you will get more detail out of the highlights and shadows with the Phase back, and the quality/texture/aesthetics/feel of those shadows and highlights is judged by most as being more pleasing/natural and less "digital".
*Again I'm not claiming Phase is the only brand for which this is true; I just prefer to make claims that I have personally verified.
Doug Peterson (e-mail Me)
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Head of Technical Services, Capture Integration
Phase One, Canon, Apple, Profoto, Eizo & More
National: 877.217.9870 | Cell: 740.707.2183
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